Knife-edge bearing for weighing apparatus.



B. G. HEDMAN.

KNIFE EDGE BEARING FOR WEIGHING APPARATUS.

APPLICATION FILED MAY 2, 1913.

1,109,838. atented Sept. 8, 1914.

a A E Wfizmma I 1x20622502 Mr W W 'ERIK GUSTAF HEDMANfOF S TQGK HOLM, SWEDEN.

KNIFE-EDGE BEARING roe WEIGI-IING APPARATUS.

Specification of Letters Patent. Application filed. May 2, 1913. Serial No. 765,028.

Patented Sept. 8, 1914;

usually constructed, the 'lmife edge is, ar-

ranged to bear upon a flat or curved surface or against the bottom of a V-groove; but in all these forms there is the disadvantage that the lmife-edge is liable to lateral displacement which, in the case of machines inwhich theflloadis transmitted through a system of leverages, may interfere with the accuracy of the machineto an appreciable extent. In the case of a V-groovedateral displacement is liable to occur owing to the fact that a perfectly sharp corner cannot be formed at the bottom of the groove. A

further disadvantage of the usual form of knife-edge is that, unless the bearing surface 1s flat or of acurve hav ng a relatively large radius or 1s in the .form of a V-groove 1n which the faces of the V are set at a very open angle, the knife edge needs to be of a very acute angle, and therefore isvery liable to wear. H I

The object of the invention is to provide a bearing of the knife-edge type in which some or all of the above disadvantages are eliminated and which is nevertheless very easy to "manufacture. a i

The. invention will be clearly described with reference to the drawings herewith which illustrate convenient embodiments thereof. v p f y Of these drawings: Figure 1 is aside elevation of a practical form of my inven tion. Fig. 2 is a right hand end view. Fig.

3 is a vertical section taken on the line a 00 of Fig. 1 looking in the direction. of the arrow at; Fig. 4 is a longitudinal sectional view to an enlarged scale the section beingtaken inthe plane indicated by the line 3 y of Fig. 3 and looking in the direction of the arrow 6 v(Fig. 3) and Figs. 5 and 6 illustrate a modified form of knife edge.

The bearing member A is formed from a plaincylindrical bar, the surfaces B B and C C being formed thereon by filing, milling, grinding or in other convenient ,manner.

The surfaces B B lie the same plane,

while the surfaces 0 0 lie in another plane i which is conveniently at right angles to the first. As clearly shown in the figures all the surfaces pass throughthe, axis of the barA. I

is the knife-edge member formed of two plates E F of which the plate E has the middle part of its lower edge cut away as shown in Fig. 1, so as to be clear of the bearing portion A except for downwardly extending portions 6 e which bear upon the surfaces B B. The plate F has portions of its lower edge cutaway as shown in Fig. 4 so as to leavedownwardly projecting portions f 7 which bear upon the surfaces G C. The plates E Fare fastened together face to face by rivetsd. It will be seen by reference to Figs. 2 and 3 that theplate E bears on thesurfaces B B only at its righthand bottom'edge and, that the angle of theedge approximates to a right angle. It is therefore easy to grind the edge very, accurately to a straight line afterthe two parts have been brought and secured together, and owing to the angle ofthe edge being a right angle it will have considerable strength and will therefore be much less liable to damage thanthe knifeedges ofordinary knife-edge bearings. The plate F in like manner needs only to have its heft-hand bottom edge ground to a straight;

It will be seen that so long as the plates. have plane surfaces at the faces which come together, their bearing edges will come accurately into the same straight line;

The fact that the surfaces BB and C G intersect in the same straight line, namely the-axis of the bar A in the embodi f ment illustrated and that the inner bottom 7 edges of the plates E and F are also inone straight line insures that the lmife edge portion as a whole turns very accurately about a single axis, namely that of thebar.

A in the example shown, and thus the bear ing is extremely sensitive andcanbe employedin connection withweighing apparatus of a class which is designed for very great sensitiveness. The construction also allows of a very great angular movement of the knife-edge portion in relation to the bearing portion. I

In lieu of securing the plates Ev and F'together by riveting, it will be understood that these two superposed plates may be integral with each'other, being formed from a single sheet open along its length and folded over as illustrated in Figs. 5 and 6. In this construction the knife edges are ground after the folding operation. The claims are de signed to cover this construction as well as the construction where the two plates are made from separate sheets. 7

It will be seen by reference to Fig. 4; that the portions f taper inward in an upward direction and that the grooves out in the bar A in forming-the surfaces 0 C taper outward in an upward direction, so that the portions f touch the bar A only at the bearing edges. In a similar manner the portions 6 e are prevented from touching the bar A except at the bearing edges.

Endwise movement of the knife-edge portion relative to the portion A can be prevented by insuring that both a right hand and left hand bottom corner of the various bottom corners of the portion 6 e, f f touch the walls of their respective grooves.

It will be seen by reference to Fig. 1 that forming a wall between adjacent bearing surfaces adds considerably to the strength of the'bearmg portion; because, if the hearing faces touched each other the bearing portion would have a very small cross sectional area at the point of contact. If in such case the faces were at right angles to each other the cross sectional area would be only one quarter of the full cross-sectional area of the original cylinder.

It will, of course, be understood that four surfaces are not essential but in ordinary cases will be necessary to provide the equivalent of at least three surfaces, one or more surfaces lying between and at an angle to two or more other surfaces which should be parallel to each other or approximately so, as otherwise the knife-edge could not be, steadied upon the bearin Having fully described my invention what I claim and desire to secure by Letters Patent is 1. In a knife edge bearing for a weighing apparatus, a bearing member comprising two or more bearing faces set at an angle one to another and all containing a common straight line, and a knife edge membercomposed of two plates whereof the adjacent faces come together and are formed substantially as planes, one ormore of the knife edges being formed in one of said plates and straight line and adapted to contact with the bearing along said line.

2. In a knife edge bearing for weighing apparatus, a bearing member comprising two or more bearing faces set at an angle one to another and all containing a common straight line, walls or partitions each of which separates one bearing face from another, and knife edge member adapted to bear on saidbearing faces, and having gaps therein to bridge over said walls or partitions. 7

3. In a knife edge bearing for weighing apparatus, a bearing member comprising two or more bearing faces set at an angle one to another, and all containing a common straight line, walls or partitions each of which separates one bearing face from another, and a knife edge member having gaps therein to bridge over said walls or partitions, said gaps leaving projections of the knifeedge member, each projection being adapted, to bear on one of the bearing faces and one or more of the ends ofsaid projections adapted to touch a wall or walls aforesaid only atthe plane of the respective bearing surface whereby endwise movement of the knife edge portion relative to the bearing portion is prevented without introduction of friction.

4. In a knife edge bearing for a weighing apparatus, a bearing member comprising two or more bearing faces set at an angle one to another and all containing a common straight line, walls or partitions each of which separates one bearing face from another, and a knife edge member having gaps therein to bridge over said walls or partitions, said gaps leaving projections forming the knife edges, each projection being adapted to bear on one of said bearing faces, adjacent ends of a wall and gap touching at the plane of said bearing surfaces and being thence divergent whereby endwise movement is prevented and radial contact and friction avoided.

5. In a knife edge bearing for a weighing apparatus, a bearing member comprising two or more bearing faces set at an angle one to another and all containing a common straight line, walls'or partitions each of which separates one bearing face from another, and a knife edge member having gaps therein to bridge over said walls or partitions said gaps leaving projections of the knife'edge member, each projection being adapted to bear on one of the bearing faces, adjacent ends of a wall and gap touching at the plane of said bearing surfaces, the

' ends of the wall being thence sloped away from the ends of the gap, whereby endwise movement is prevented and radial contact 7 and friction avoided. another or others 1n the other plate and all said knife edges being disposed in a single 6. In a knife edge bearing for a weighing apparatus, .a bearing member comprising two ormore bearing faces set at an angle one to, another and all contammg a common straight line, walls or partitions each of which separates one bearing face from another, and a knife edge member having gaps therein to bridge over said walls or partitions, said gaps leaving projections of the knife edge member, each projection being adapted to bear on one of the bearing faces,

adjacentends of a Wall and gap touching signed my name this 19 day of April 1913 i I the plane of said bearing surfaces and :being in the presence of two subscribing .Witthence sloped in opposite directions one nesses. I i away from the other, whereby endWise ERIKGUSTAF HEDMAN. 5 movement is prevented andmdial contact Witnesses:

and friction avoided. CARL, ALBIN WIKLUND,

.In Witness whereof I have hereunto JOHN ALBER ELDMAN.

bopies of this patent'may be obtained for five cent; each," byaddressin'g tha Commissioner 01' Patents,

Washington D. C. f t 

